The present invention relates to a means for laterally guiding or fixing the angular position of two telescopic parts relative to each other. More specifically, the present invention relates to a hydraulic guidance actuator assembly for a crane jib.
Telescopic parts, more particularly those as used for vehicular cranes, are provided with a fixing means so that during installation, or less frequently also when repair is needed, an extensible telescopic part can be set relative to the supporting telescopic part guiding the extensible telescopic part, for example, by a clasping action. These fixing means need to be designed in part so that they act perpendicular to the main direction of deformation of the telescopic parts, i.e., in the horizontal plane for example, in the case of a horizontally located telescopic jib (crane jib in the down condition), perpendicularly loaded downwards. This means that the location of a telescopic part can be maintained in this horizontal plane by the fixing means to achieve optimum alignment of two telescopic parts relative to each other.
The terms "horizontal" and "vertical" as orientation indications used in this context relate to the down condition of a jib consisting of telescopic parts, i.e. oriented horizontally substantially parallel to the ground.
Conventional fixing means for telescopic parts having substantially rectangular cross-sections comprise in the lower cross-sectional area of an inner telescopic part stoppers applied to both sides which are also termed guide plates. In this arrangement an adjuster applied to the outer telescopic part consists of a lockable setscrew, the face surface area of which, when screwed in, comes into contact with the main surface area of the stopper. The contact surface area between the setscrew and guide plate runs parallel to the vertical, main direction of deformation, so that also in loaded operation of the jib it can be assured that contact is made with this surface area, thus defining the position.
Accordingly, in this fixing arrangement the setscrew is screwed into a setscrew hub provided in the outer telescopic part until the setscrew is in snug contact with the guide plate at its face surface area. Since it is accessible on the outside of the outer telescopic part such a fixing means offers greatly facilitated handling.
More recently, however, jib profiles have become popular comprising lower rounded shell sections which are usually curved outwards, thus causing major problems in continuing to use the conventional system for a fixing means, as described above, in the region of lower, curved telescopic part shells.
In attempting to provide a setscrew accessible from without in such lower curved regions, which can be screwed in horizontally so that the vertically oriented face surface area is in turn able to come into contact with a vertically oriented guide plate bearing surface the collar and the guide in the region of the setscrew would have to be provided with large openings to permit passage of the setscrew. This has an additional negative effect on the steady-state loading capacity of the lower shell.